Prof. Ajit Kembhavi, a well known astronomer of the country, former Director of Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, gave an expository online talk on the subject on 28th January. This lecture on popular astronomy was conducted by the Society for Promotion of Science & Technology in India (SPSTI) in collaboration with Chandigarh Chapters of National Academy of Sciences India (NASI) and Indian National Young Academy of Sciences (INYAS). Prof. Kembhavi’s talk was entitled “From Galileo’s Telescope to James Webb Space Telescope: The Forward March of Astronomy”. Prof. Jasjeet S. Bagla, Dept. of Physical Sciences and Dean, IISER Mohali, was invited as Guest of Honour.
Prof. Kembhavi said that that Galileo, who was not the inventor of telescope as is popularly believed, but was the first one to use it for sky-gazing and to view the sunspots in the year 1612, also observed the satellites of Jupiter and discovered stars in the Milky-way Galaxy. He found that the phases of Venus look similar to that of the Moon.
Talking about the Great Forty-Feet Telescope which was constructed by William Herschel in Slough during 1785-89, Prof. Kembhavi apprised that it was the largest telescope in the world for over 50 years. Herschel was the first one to map the shape of the galaxy. He also discovered the planet Uranus.We need to understand the entire electromagnetic emission spectrum from an object to get a good idea of its structure.
The Giant Metrewave Radio Telescope (GMRT) and AstroSat (2015)have emerged as prominent astronomy facilities of India, which are also used by the international scientific research community. He apprised the audience about ADITYA L1, which is a solar mission to be launched in 2023. The Thirty Meter Telescope (TMT) will be the world’s most advanced ground based optical and near-infrared observatory and India is one of the major partners in this project.
The Himalayan Chandra Telescope located at Ladakh, the Palomar 5m Hale Telescope located in California and the Keck Telescope in Hawaii are other major telescopes in the world. Apart from ground-based astronomy, which depends on the visible spectrum and radio waves of the electromagnetic spectrum, use of multi-wavelength astronomy is enormously important in the study of physical phenomena in the universe because Gamma rays, X-rays, ultraviolet rays and infrared spectrum emitted by distant objects are much affected by the atmosphere of the Earth. This brings about the need of telescopes in space.
The Hubble Space Telescope which was launched in space on 24th April, 1990 has conducted over 1.5 million observations. The James Webb Space Telescope was launched on December 25, 2021 and is stationed at 1.5 million kilometers away from the earth. The telescope releases awesome images such as that of ‘pillars of creation’ in the Eagle Nebula which is 8500 light years away.
The session was much appreciated by the whole audience (over 55 on Zoom), comprising of students from school and college, astronomers and researchers, was followed by a healthy question answer session. Also present on the occasion were Shri Dharam Vir, IAS (Retd.), Prof. Arun K. Grover, Ex-Vice Chancellor of Punjab University and Prof. Keya Dharamvir, President, Vice President and General Secretary respectively of SPSTI. The session was attended by many others from various academic and research institutions of the country.